The goal of the current research is to investigate auditory constraints on general learning mechanisms (GLMs) underlying infant language acquisition. There have been numerous demonstrations of the importance of GLMs in word segmentation, and more recently this approach has been extended to phoneme acquisition. The primary critique of GLMs is that they are too computationally powerful. Without constraints, it would be difficult to extract only meaningful regularities, making the task of language acquisition a potentially intractable problem. Auditory constraints may provide a good framework on which GLMs can operate, facilitating the task of language acquisition. The first Specific Aim of the research proposed in this application is to examine the relationships between auditory sensitivities and distributional learning during phoneme acquisition. 7.5-month-old infants will be exposed to either a unimodal or a bimodal distribution of speech sounds. A habituation procedure will be used to test the hypothesis that the presence of a region of increased auditory sensitivity at a category boundary will facilitate phoneme acquisition. The second Specific Aim is to investigate the relationship between rhythmic grouping biases and statistical learning during word segmentation from fluent speech. Following familiarization to an artificial language that contains both statistical and rhythmic cues to words boundaries, 6.5- and 8.5-month-old infants are expected to mis-segment the statistical words in the language if the statistics and the perceived rhythmic grouping are inconsistent. Age effects are expected only if linguistic experience is necessary for auditory rhythmic grouping biases to emerge. The third Specific Aim is to assess the domain generality of the mechanisms described in the first and second aims. Non-speech stimuli will be used to assess the generality of distributional and statistical learning in the same types of category learning and segmentation tasks. The goal of this research is to understand how the auditory system of a typically developing infant structures language learning. In some atypical populations, it is unclear whether language acquisition is delayed because the auditory system is compromised or because the mechanisms responsible for learning are compromised. Future studies will use these tasks to assess learning in atypical language learners (e.g., young children with phonological disorders, toddlers with cochlear implants, infants at risk for language impairments), with the eventual goal of developing new interventions for use in clinical populations.